Goofs: The Skishtari arrive over Hexford via wormhole, so what have UNIT been investigating for the past few weeks given there are no craft to track? And surely they would have the technology to scan for their 'gene egg' device without extracting the extended area?

Dialogue Triumphs: "Occupational hazard with time travellers, I'm afraid. You don't know how many you're going to get"

"You wait all year for one Time Lord to arrive, then all of a sudden two turn up!"

Continuity: It's been nearly nine months since the Doctor was in Hexford. There is a village store (probably distinct from the mini market) Dr2 orders humbugs. The old rectory lies over Hexford Green, behind the minimart and toward the main road, beyond is Hexford Woods. The church hall doubles as the village meeting place. There are graves in its churchyard (which are also uprooted by the Skishtari ship.) Dierdre Llanrechra's house is "on the other side" of Nest Cottage. Her cousin Tish Madoc, is a celebrated novelist of "racy" stories, according to Rev Tonge. Dierdre and Tish's families were from Hexford centuries ago, but mostly moved about "after that business with the dragon - or at least that's what they say". The Doctor has met Dierdre before, telling her that the sheep's jaw she attempted to sell at a jumble sale wasn't a sheep's jawbone at all. Tish complains that Hexford is mostly full of old ladies (male voices or various approximate adult ages), besides the "fey" Reverend Tonge. The Doctor usually lands the TARDIS in the same spot; next to the picnic table in Nest Cottages back section. In the cottage are paintings on the wall and a hat stand in the hallway. There is a gravel path outside (at the front?) There is a carpeted hallway and crockery on a Welsh dresser. Kitchen is at the back of Nest Cottage, through its window one might see the hollyhocks and back garden of Tish Madoc's home. The Doctor's and Wibbs' rooms are upstairs in the Cottage. There is a hedge separating the two buildings, and Tish's back garden hosts bees in tall, painted chalet hives.

The Skishtari spaceship is a silvery disc about half a mile across, with the Serpent Crest upon its underside. The ship sends jagged lines of magnetic energy which connect with the biomesh trees as a sort of tractor beam. The Doctor describes the Skishtari gene egg as "sacred". The Doctor and Beulin buried the Skishtari gene egg in a lead casket, where it has lain under Nest Cottage for 150 years.

Biomesh plants are black and glossy, spindly like saplings. They have roots like steel tentacles which intermesh deep underground. They generate their own gravity fields (are they a Skishtari invention?) The 'Second Doctor' has been growing the biomesh trees in UNIT's nurseries for weeks.

Mike has been brought out of retirement and has a deputation of two UNIT soldiers and was asked specifically to come out of retirement as the 'Doctor' had asked for someone "from the old days" (can we assume the Brig has died by this time, too? Perhaps Mike is here because of his familiarity with Hexford?)

Mrs Wibbsey danced the Can-Can at the village church Easter show and has developed an aversion to bees.

The 'Second Doctor' mentions Cybermen and Yeti in the Underground, and the Great Intelligence on the Bakerloo Line to Mike, implying that Mike was there (this ought to have been a giant clue to Mike Yates as UNIT didn't exist at the time!) Though Mike says he's known "several models" of Doctor, he doesn't know this one, although he caught a glimpse of him once, "during the business with the Anti Matter". Mike believes he has his own TARDIS.

The Doctor projects a gravity bubble using the TARDIS to counteract the Skishatri/biomesh tractor beam.

Links: Dierdre is introduced by name in The Broken Crown. For a potential forebear of Tish and Dierdre, see the same story. The 'Second Doctor' mentions Cybermen (The Invasion) and the Great Intelligence and Yeti (The Web of Fear) Mrs Wibbsey's aversion to bees and insects is of course a result of her dealings with the Hornets (Hornets Nest, Demon Quest)

Location: Hexford, a Thursday in August, 2011.

The Bottom Line: 'This is it, Mrs Wibbsey. One final chase, across time and space!"

A wonderful opening, concentrating on the star of this series, the increasingly self-aware Mrs Wibbsey. Her initial paranoia sets the scene for an engaging and building story, particularly her brush with a would-be Second Doctor. David Troughton hits most of his father's spots, but comparisons with Richard Hurndall will inevitably appear. It's good to hear Mike back though!